13mentaculus, you mentioned in another thread that you have a BS in physics. Now I must admit, I don't know what a BS is, and it just can't be short for what I first thought of! But I assume it involves something that makes you much more adept in physics then I am. So therefore I have a question for you.

I had a discussion with a colleague of mine a few days ago. He claims that if you have two pipelines of different diameters, say 2" and 4", then the 4" pipe needs to have a thicker wall than the 2" pipe in order to hold the same pressure. My position is that he is wrong. From what I remember from school its the pressure that matters, not the volume.

I'm sorry if i'm reading this incorrectly or if i'm just stupid, but it seems to me like you're wrong. If there's a 4" pipe to accommodate a certain pressure, if you get a smaller pipe that has to handle that same pressure, odds are, it needs a thicker wall.

(18-03-2011 01:19 PM)ThinkingNorseman Wrote: He claims that if you have two pipelines of different diameters, say 2" and 4", then the 4" pipe needs to have a thicker wall than the 2" pipe in order to hold the same pressure. My position is that he is wrong. From what I remember from school its the pressure that matters, not the volume.

I don't know about pipes and pressure, but when you double the height of a pillar you need to make it more than double its diameter to make it hold double the weight. Based on this my guess would be that he is right because there is more pressure on the larger pipe because there is more surface area inside the pipe.

I hope someone can verify the answer because I want to know. My best guess is still a guess.

When I find myself in times of trouble, Richard Dawkins comes to me, speaking words of reason, now I see, now I see.

I know this isn't directed towards me, but I can't let an engineering question pass by .

A larger diameter pipe needs to be thicker to hold the same pressure. Pressure is force/area, so if you increase the diameter, you increase the area and the overall magnitude of the force pushing outwards on the pipe is larger in the bigger pipe than the smaller one.

There is an equation for it, I can't remember it off the top of my head but essentially it's:

Of all the ideas put forth by science, it is the principle of Superposition that can undo any power of the gods. For the accumulation of smaller actions has the ability to create, destroy, and move the world.

Good thing Glaucus saved the day then.
My colleague argued that there was a need for thicker walls in the pipe because of the overall pressure that was acting on it due to increased surface area. I argued that it also meant that there was more pipe wall to carry the load. oh well.. guess I was wrong again. He's going to love this when I tell him.